This invention relates to an automatic coating apparatus which is suitable for use, for example, in coating objects such as vehicle bodies and the like.
Generally, coating objects like automotive vehicle bodies (hereinafter referred to simply as, xe2x80x9cvehicle bodiesxe2x80x9d for brevity) are coated by an automatic coating apparatus which is installed within a coating booth. The automatic coating apparatus of this sort is largely constituted by a working mechanism which is put in action in relation with coating objects which are delivered to the coating booth by a conveyer, and a coater or sprayer unit which is mounted on the working mechanism and arranged to spray paint toward the delivered coating objects.
In this connection, as a working mechanism, it has been the general practice to employ a coating robot which is provided with a plural number of joints to carry out a coating operation on vehicle bodies according to contents of teaching, or a reciprocator which is arranged to reciprocate across a certain range in coating vehicle bodies. In order to follow the movement of vehicle bodies on a conveyer in the course of a coating operation, the working mechanism is usually mounted on a tracking mechanism and thereby moved along the conveyer.
Further, resorted to as a sprayer in most cases are bell-shape sprayers which are arranged to atomize paint mainly by means of a bell-shaped cup which is put in high speed rotation. There have been a diversity of bell-shape sprayers which differ from each other in diametrical size of the bell cup as well as in spurting direction and feed rate of shaping air which forms a spray pattern. A suitable bell-shape sprayer for a coating robot is selected depending upon various conditions such as the shape of an object to be coated, the type and color of paint to be used and coat finishing conditions. Therefore, for coating exterior panels of a vehicle body, for example, it is the general practice to use a bell-shape sprayer with a bell cup of a large diameter, which is suitable for coating broad surface areas and can produce satisfactory coatings in finish quality. On the other hand, for coating interior surfaces of vehicle bodies, a bell-shape sprayer with a bell cup of a small diameter is generally employed because it is more suited for spotwise coating operations.
In the case of a prior art automatic coating apparatus of this sort, different types of sprayers are employed as mentioned above, depending upon the shape of coating objects as well as upon the type and color of paint to be used. In use, each sprayer needs to be integrally mounted on a working mechanism like a coating robot, so that it has been necessary to provide a plural number of automatic coating apparatus along a vehicle body coating line to cope with different coating conditions, despite increases in equipments cost of the production line and in machine installation space, which necessitate to provide a coating booth of an extremely large size.
On the other hand, in order to solve these problems, various attempts have thus far been made to replace the sprayer each time when changing the paint color or conditions of a coating operation, as disclosed in Japanese Patent Laid-Open No. S60-122071 and H4-83549.
However, the prior art automatic coating apparatus, which are arranged to replace a sprayer as a whole by a different type, require to provide a plural number of diverse sprayers for each paint color, that is to say, to provide a vast number of sprayers. In addition, the prior art automatic coating apparatus has a drawback that a great deal of labor and time is required in replacing the entire sprayer each time.
Further, in this regard, there have been known in the art cartridge-type coating apparatus which are arranged to mount a sprayer fixedly on a coating robot, while setting a paint cartridge of a selected color replaceably on the sprayer in order to obviate the troublesome job of replacing the entire sprayer (e.g., as disclosed in Japanese Patent Laid-Open No. S63-175662 and H8-229446).
In the case of an automatic coating apparatus which is disclosed in the above-mentioned Japanese Patent Laid-Open No. S63-175662, a paint cartridge which is selected from an assortment of paint cartridges is replaceably loaded on a coating machine before starting a coating operation. At the time of cartridge replacement, by way of a hose which is connected to the sprayer, a wash fluid is supplied to wash away a previous color which has deposited on the sprayer.
On the other hand, an automatic coating apparatus which is disclosed in the other Japanese Patent Laid-Open No. H8-229446 is provided with a plural number of paint cartridges which are replaceably set on a bell-shape sprayer.
However, in the case of these prior art automatic coating apparatus, it is necessary to provide a hose along a robot arm to supply therethrough a wash fluid for washing the sprayer, despite the difficulties of routing the hose to and along the robot arm in a tidy way. In addition, the wash fluid supply hose which droops down between the robot arm and the sprayer may cause a flaw or damage to a coating object by contacting the hose during operation, or may suffer from damages or frictional wear by contacting other component parts of the apparatus.
Furthermore, in the case of a bell-shape sprayer as disclosed in Japanese Patent Laid-Open No. H8-229446, the sprayer with a bell-shape cup which is fixedly mounted on a coating robot in a fixed state requires a long washing time for cleaning the bell cup, and suffers from low productivity because a coating operation is interrupted for a long time while the bell cup is being washed.
In view of the above-described problems with the prior art, it is an object of the present invention to provide an automatic coating apparatus which is arranged to attach a diversity of bell-shape heads replaceably to a common assembly body which is mounted on a single working mechanism, thereby permitting considerable reductions in cost and apparatus installation space.
It is another object of the present invention to provide an automatic coating apparatus which permits to replace bell-shape heads in a facilitated manner and as a result to enhance the productivity of the apparatus.
It is still another object of the present invention to provide an automatic coating apparatus which permits to carry out and continue a coating operation by the use of one bell-shape head while washing another bell-shape head which was used in a previous coating operation, thus ensuring improved productivity of the apparatus.
It is a further object of the present invention to provide an automatic coating apparatus which can facilitate washing operations on bell-shape heads to a significant degree particularly in case the bell-shape heads are of a cartridge-type sprayer which is arranged to be replaceably loaded with a plural number of paint cartridges of different colors.
In order to solve the above-mentioned problems, according to the present invention, three is provided an automatic coating apparatus, which comprises: a working mechanism to be put in predetermined coating actions relative to a coating object; a common main assembly body fixedly mounted on the working mechanism to serve as a main assembly body for a number of sprayers; a number of bell-shape heads each displaceably connectable to the common main assembly body to form a bell-shape sprayers and adapted to spray supplied paint in a finely atomized form by means of a bell-shaped cup rotating at high speed; and a head changer provided within a working area of the working mechanism and adapted to hold a grip on and off the bell-shape heads at the time of replacing a bell-shape head on the common main assembly body.
With the arrangements just described, the head changer is located within a working area of the working mechanism, so that, at the time of replacing the bell-shape head which is replaceably attached to the common main assembly body, the bell-shape head can be automatically replaced by moving same to a predetermined head replacing position on the head changer through the working mechanism.
In a case where a bell-shape head is connected to the common main assembly body to form a bell-shape sprayer, the resulting bell-shape sprayer is moved by the working mechanism while spraying supplied paint from a bell cup toward a coating object.
In addition, since the bell-shape head is detachably connected to the common main assembly body, it can be replaced by other bell-shape heads of different spray patterns, depending upon the nature of coating surfaces of coating objects.
According to the present invention, the head changer is comprised of at least a couple of head gripper mechanisms, one for gripping a bell-shape head which has been transferred to a predetermined head replacing position by the working mechanism, and the other one for holding another bell-shape head in a waiting position in preparation for connection to the common main assembly body.
With the arrangements just described, upon completing a coating operation by one bell-shape head, the used bell-shape head is transferred to one of the gripping mechanisms by means of the working mechanism and detached from the common main assembly body and instead gripped on one gripping mechanism. In the next place, the common main assembly body is moved toward another bell-shape head waiting by on the other gripping mechanism by the working mechanism and connected with the new head to continue a coating operation.
According to the present invention, the head changer is comprised of head gripping mechanisms each adapted to hold a grip on and off a bell-shape head, and head washing mechanisms each adapted to wash a bell-shape head which is gripped on one of the head gripping mechanisms.
With the arrangements just described, as soon as a used bell-shape head is gripped on one gripping mechanism of the head changer, the bell-shape head including its bell cup can be cleaned by the use of a washing mechanism.
According to the present invention, the head changer is comprised of at least a couple of head gripper mechanisms, one for gripping a used bell-shape head which has been transferred to a predetermined replacing position by the working mechanism and the other one for holding another washed bell-shape head in a waiting position in preparation for connection to the common main assembly body, and at least a couple of head washing mechanisms each adapted to wash a bell-shape head which is gripped on one of the head gripping mechanisms.
With the arrangements just described, upon finishing a coating operation, a used bell-shape head is transferred to a predetermined head replacing position by the working mechanism, and gripped on one of the gripping mechanisms of the head changer. Then, another bell-shape head waiting by on the other gripping mechanism is picked up and connected to the common main assembly body by the working mechanism to continue the coating operation. In the meantime, the used bell-shape head which is gripped on one gripping mechanism, is washed by one washing mechanism concurrently with the coating operation by the other bell-shape head.
According to the present invention, the head changer is comprised of head gripping mechanisms adapted to hold a grip on and off a bell-shape head, washing mechanisms adapted to wash a bell-shape head gripped on one of the gripping mechanism, and a bearing air supply mechanism adapted to supply air to air bearing of an air motor of a bell-shape head which is gripped on one of the head gripping mechanisms.
With the arrangements just described, when a bell-shape head is gripped on one gripping mechanism of the head changer, bearing air is supplied to air bearing of an air motor of the gripped head. Accordingly, even when the bell-shape head is disconnected to the common main assembly body, the rotational shaft of the air motor is hydrostatically supported by the air bearing, thereby preventing abrasive wear or damages which would otherwise occur to the air motor.
According to the present invention, each one of the bell-shape sprayers is of a cartridge-type adapted to be replaceably loaded with paint cartridges of various colors, each one of the paint cartridge comprising a container filled with paint and a feed tube extending axially forward from the container.
With the arrangements just described, paint cartridges of various colors can be replaceably loaded into the common main assembly body of the bell-shape sprayer. In this case, the cartridge-type sprayer can feed paint of different colors through feed tubes of the respective paint cartridges.
According to the present invention, the common main assembly body comprises a cartridge loading cavity for receiving the paint cartridge and an axial feed tube passage hole to receive the feed tube, and each one of the bell-shape heads is internally provided with an axial feed tube passage hole to receive said feed tube.
With the arrangements just described, when one of the paint cartridges of different colors is selectively fitted into the common main assembly body, paint of a selected color can be fed to the bell-shape head through the feed tube which is passed into the feed tube passage holes in the common main assembly body and the bell-shape head.
According to the present invention, each one of the bell-shape heads is internally provided with an axial feed tube passage hole to receive the feed tube of the paint cartridge therein, and the head changer is provided with head gripping mechanisms for gripping the bell-shape heads along with washing mechanisms for washing the bell-shape heads while being gripped on the head gripping mechanisms, the washing mechanisms each being provided with a wash fluid supply tube to be inserted into the feed tube passage hole in the bell-shape head for spurting a wash fluid thereinto.
With the arrangements just described, when a bell-shape head is gripped on one gripping mechanism of the head changer after a coating operation, the wash fluid supply tube of a washing mechanism is passed into the feed tube passage hole of the bell-shape head, and a wash fluid is spurted out from the wash fluid supply tube to wash away deposited paint from the bell-shape head.
According to the present invention, the bell-shape heads are each internally provided with an axial feed tube passage hole to receive the feed tube of the paint cartridge, and the head changer is provided with head gripping mechanisms for gripping the bell-shape heads, washing mechanisms for washing the bell-shape heads while being gripped on the head gripping mechanisms, and bearing air supply mechanisms for supplying bearing air to an air bearing of an air motor in the bell-shape heads while being gripped on the gripping mechanisms, the washing mechanisms each being; provided with a wash fluid supply tube to be inserted into the feed tube passage hole in the bell-shape head for spurting a wash fluid thereinto, and a turbine air supply passage for supplying turbine air to the air motor of a bell-shape head being washed, thereby keeping the bell cup in rotation during a washing operation.
With the arrangements just described, when a bell-shape head is gripped on one gripping mechanism of the head changer after a coating operation, bearing air is supplied to the air bearing of the air motor from the bearing air supply mechanism to hydrostatically support the rotational shaft of the air motor. Further, the wash fluid supply tube of a washing mechanism is passed into the feed tube passage hole in the bell-shape head, and the turbine air supply passage is connected to the air motor of the bell-shape head. Then, through the turbine air supply passage, turbine air is supplied to the air motor of the bell-shape head, so that a bell cup on the bell-shape head is kept in rotation while a wash fluid is spurted out from the wash fluid supply tube to wash away deposited paint from the head including the bell cup.
According to the present invention, the common main assembly body is provided with a head connecting portion to which one of the bell-shape heads is disconnectibly connected, and an air suction passage in communication with a vacuum space formed between the head connecting portion and a connected bell-shape head, sucking out air from the vacuum space through the air suction passage to hold the bell-shape head fixedly to the common main assembly with suction grip.
With the arrangements just described, upon connecting a bell-shape head to the head connecting portion of the common main assembly body, air is sucked out through the air suction passage from a vacuum space which is formed between the head connecting portion and the bell-shape head, thereby to pull and hold the bell-shape head against the common main assembly body fixedly and stably by a suction grip. On the other hand, at the time of disconnecting the bell-shape head from the common main assembly body, air is supplied to the vacuum space to cancel the suction grip.
According to the present invention, the common main assembly body has a feed tube axially projected on the front side thereof, while the bell-shape heads are each internally provided with an axial feed tube passage hole to receive the feed tube.
With the arrangements just described, paint is of a desired color can be supplied through a color changing valve device or the like, and the supplied paint spurted out from the feed tube of the common main assembly body and sprayed by the bell-shape head.
According to the present invention, there is also provided an automatic coating apparatus, which comprises: a working mechanism to be put in predetermined coating actions relative to a coating object; a common main assembly body fixedly mounted on the working mechanism to serve as a common main assembly body for a number of bell-shape sprayer; a number of bell-shape heads each displaceably connectible to the common main assembly body to form bell-shape sprayers and adapted to spray supplied paint in a finely atomized form by means of a bell-shaped cup rotating at high speed; a number of paint cartridges of different colors, each having a container filled with a specific paint color, a feed tube axially extended out on the front side of the container for insertion into the common main assembly body and one of the bell-shape heads; and a head changer provided within a working area of the working mechanism and adapted to hold a grip on and off the bell-shape heads at the time of replacing a bell-shape head on the common main assembly body; and said bell-shape sprayers are formed cartridge-type bell-shape sprayers which are replacabley connected a number of paint cartridge of different colors to said common main assembly body.
In a preferred form according to the present invention, the working mechanism is a coating robot or a coating reciprocator provided in a coating booth, and the common main assembly body is mounted on a distal end portion of the coating robot or reciprocator.
With the arrangements just described, by moving the coating robot or coating reciprocator in predetermined actions, the bell-shape head which is connected to the common main assembly body, on a fore distal end of an arm of the robot or reciprocator, is moved along coating surfaces of a coating object to spray paint thereon.